| Age (years)* | n | % |
| 10 | 1 | 0.3 |
| 11 | 1 | 0.3 |
| 12 | 42 | 13.8 |
| 13 | 72 | 23.7 |
| 14 | 64 | 21.1 |
| 15 | 82 | 27.0 |
| 16 | 24 | 7.9 |
| 17 | 18 | 5.9 |
| Total | 304 | 100 |